If there is a space occupying lesion in a patient's orbit, it pushes his eye forwards. Proptosis is always serious, and it can be difficult to diagnose; so it is fortunate that it not common. Some of its causes (orbital cellulitis and Burkitt's lymphoma) need chemotherapy. Most of the patients who need surgery are either going to die from malignant tumours anyway, no matter what is done, or they have slow-growing benign tumours, which you have time to refer. So your ability to help a patient with proptosis is limited; but you should try to make a diagnosis.

Proptosis can occur slowly over years, or rapidly over days. Its causes vary geographically, and with the age of the patient. Here they are, the more common ones first; the later ones are mostly very rare:

An adult may have: (1) A retrobulbar haematoma following an injury (common, 60.8). This is only an incident in a head injury, and the diagnosis is obvious. (2) A mucocele of his frontal sinus (the commonest cause), due to an infection followed by an obstruction, which prevents his sinus draining into his nose. (3) Orbital cellulitis, or an orbital abscess, usually following frontal or ethmoid sinusitis (5.5), or occasionally trauma. (4) A pseudotumour of his orbit due to a granuloma of unknown cause. (5) An epidermoid or dermoid cyst, which may be of the ''dumb-bell' type, and extend into his anterior cranial fossa. Don't operate on these, unless you are skilled enough to dissect widely, and have made an accurate diagnosis. (6) A mixed lachrymal tumour (lachrymal adenoma). (7) A haemangioma or hamartoma; you may be able to empty a haemangioma temporarily by pressing it back into his orbit. (8) A hydatid cyst, if he comes from an area where these occur (31.13). (9) Cavernous sinus thrombosis (5.5). (10) A secondary tumour. (11) A malignant melanoma (32.20). (12) Carcinoma of his maxillary or ethmoidal sinuses (32.39) invading his orbit. (13) The hyperophthalmopathic form of thyrotoxicosis (dysthyroid eye disease, Graves's disease). (14) A meningioma of his sphenoid.

A child may have: (1) A retinoblastoma in the first 5 years of his life (32.7). (2) Acute ethmoiditis, commonly when he is about 2. (3) Burkitt's lymphoma, if he comes from the ''Burkitt zone' (32.3). He will probably have a jaw tumour also. (4) A rhabdomyosarcoma (32.9). (5) Some other kind of lymphoma (32.4, 32.5). (6) A neuroblastoma. (7) A secondary tumour.

You can treat orbital cellulitis, abscesses, and cavernous sinus thrombosis (5.5) with systemic antibiotics. If you diagnose a retinoblastoma (32.7) early enough, you can enucleate the globe. Burkitt's lymphoma usually responds dramatically to chemotherapy.

Fig. 24-10 PROPTOSIS. A, and B, Burkitt's lymphoma, before and after treatment. C, proptosis, cause not yet established. D, carcinoma of the maxillary antrum extending into the orbit. A, B, and D, after Parsons GA, and Berg D, ''Proptosis and orbitotomy in Papua New Guinea', Tropical Doctor 1977;7:129[nd]33. C, kindly contributed by Edward Kasili.

PROPTOSIS HISTORY. Long history? (benign lesion). Short history? (malignant lesion or acute infection). Acute onset with pain? (infection).

EXAMINATION. Sit the patient down, stand behind him, look down on his eyes from above, and observe the relative positions his globes. This will help to distinguish pseudoproptosis, due to the relative widening of one palpebral fissure.

Hold a ruler horizontally, and measure the position of each cornea from the midline. If he has two proptosed globes, and they are both equidistant from the midline, he probably has thyrotoxicosis (the most likely cause of bilateral proptosis). If they are not equidistant, one globe has probably been pushed out of place by an orbital mass.

Examine his fundi for papilloedema and optic atrophy. Search him for signs of a primary malignant tumour.

CAUTION ! Don't confuse proptosis with a staphyloma due to a neglected corneal ulcer (24.3). His normal intraocular pressure has caused his previously weakened cornea to bulge, in a manner which you can mistake for a tumour. His globe is however in its normal position.

X-RAYS may demonstrate: (1) Erosion of the bones of his orbit. (2) Sclerosis (typical of a meningioma). (3) Calcification (sometimes in a retinoblastoma).

BIOPSY may be practical.

If a tumour is palpable externally, explore over it and take a biopsy, except for lachrymal adenomas, which should never be biopsied.

If it is not palpable externally, a lateral orbitotomy which splits his temporal bone may be indicated. Refer him.

DIAGNOSIS AND MANAGEMENT. See elsewhere for the management of orbital infections (5.5), especially draining pus (drainage through the lower or upper fornix is usually best), retinoblastoma (32.7), and Burkitt's lymphoma (32.3).

Acute ([lt]3 months) in an adult: orbital cellulitis, trauma, pseudotumour.

Acute ([lt]3 months) in a child: acute ethmoiditis, retinoblastoma (0[nd]5 years), Burkitt's lymphoma (5[nd]15 years).

Chronic ([mt]3 months) in an adult: frontal mucocele, thyrotoxicosis, lachrymal tumour, meningioma.

If his proptosis arose acutely, and his lids are red and swollen, perhaps with a fever and tachycardia he has orbital cellulitis, or an orbital abscess. Give him systemic antibiotics. If he has an abscess drain it.

If a child of about 2 years has sudden unilateral proptosis, with swollen lids and conjunctiva, fever and tachycardia, suspect acute ethmoiditis. Give him systemic antibiotics.

If he is very sick and with an acute pulsating proptosis, which may be unilateral initially, but soon becomes bilateral, with engorgement of the veins, and total inability to move his eye, perhaps with an associated meningitis, suspect cavernous sinus thrombosis (5.5).

If he has a swelling which has enlarged slowly (weeks or months) in the superior nasal quadrant of his orbit, pushing his eye downwards and outwards, he probably has a mucocele of his frontal sinus (common). Drain it through an approach between his periosteum and his frontal bone, keeping outside his orbit. Enter his sinus and drain the mucopus. Place a drain from his sinus into his nose. Suture his skin in layers. Remove the drain at 6 weeks.

If he is between 15 and 35, and his proptosis occurred over several weeks or months, suspect a pseudotumour. The diagnosis is largely by excluding other causes. It will respond well to prednisolone 80 mg daily for 1 week, falling slowly to 5 mg daily by the 4th week. Maintain him on 5 mg a day for several months, or it will recur.

If he has a swelling of the upper lateral quadrant of his orbit, pushing his eye downwards and inwards, which has grown slowly over many months or years, he probably has a lachrymal adenoma. Don't be deceived by the small mass of tumour palpable externally: most of it will be inside his orbit behind his eye. It needs removing through a lateral orbitotomy. Refer him.

If the proptosis of thyrotoxicosis does not respond to medical or surgical treatment (21.8), try high dose systemic steroids. If this fails, refer him for the surgical decompression of his orbits.

SYMPTOMATIC TREATMENT FOR HIS EXPOSED CORNEA. Examine his cornea to make sure that it is not ulcerated. Apply antibiotic eye ointment 3 or 4 times daily, and especially at night. If necessary, protect it by tarsorrhaphy (58.28). Padding can be dangerous, because the pad may abrade and ulcerate his cornea.